Technology / Bi-Directional Patent
Bi-Directional Power Architecture — The Patent
A conventional UPS either charges or discharges — never both simultaneously. Su-vastika’s patented bi-directional architecture allows the ERD to accept grid power, charge the battery bank, supply the lift motor, and even recover regenerative energy from motor deceleration — all at the same time.
What Is Bi-Directional Power Flow?
In a standard single-direction UPS, current flows one way: from the AC grid, through the rectifier, into the battery, and from the battery through the inverter to the load. Charging and discharging happen sequentially, not simultaneously. When the grid is present, the battery charges. When the grid fails, the battery discharges.
A bi-directional system breaks this constraint. The same power electronics path can carry current in either direction, at the same time if needed. In an ERD context, this means:
- Grid → Battery: Charging the battery bank from the grid
- Battery → Motor: Powering the lift motor from battery
- Motor → Battery: Recovering regenerative energy when the lift decelerates
- Grid → Motor + Grid → Battery: Simultaneously powering the motor and charging batteries from the grid
The patent covers the specific circuit topology and control algorithm that enables this multi-directional power flow without conflicts, instability, or excessive loss.
Regenerative Energy Recovery
A lift motor decelerates by using the motor as a generator — converting kinetic energy back to electrical energy. In a conventional lift installation, this regenerative energy is dumped into braking resistors and wasted as heat.
With bi-directional power architecture, the ERD captures this regenerative energy and routes it back into the battery bank. In a busy building with frequent lift cycles, this can recover 10–15% of total lift energy consumption. The net effect is extended battery backup time per charge and reduced electricity consumption.
Power Stage
Power flows in all directions simultaneously — grid charges battery while powering motor; regenerative braking returns energy to battery.
How This Differs from a Standard UPS
| Capability | Standard UPS | ERD (Bi-Directional) |
|---|---|---|
| Simultaneous charge + discharge | ❌ No | ✅ Yes |
| Regenerative energy recovery | ❌ No | ✅ Yes (10–15%) |
| Output while charging | Limited | ✅ Full rated power |
| 3-Phase motor support | Usually no | ✅ Native 3-phase |
| Battery life management | Basic | ✅ Intelligent DoD control |
| Solar input integration | Rare | ✅ Patented integration |
| IoT monitoring | Optional | ✅ Built-in |
The Patent Story
Su-vastika Systems, based in Ghamroj, Haryana, filed the original bi-directional ERD patent after years of field experience with conventional lift backup systems. The core insight was that lift motors are fundamentally different from typical UPS loads — they are high-current, variable-frequency, regenerative machines that demand a bidirectional power interface.
The patent covers not just the hardware topology but the control algorithm — specifically how the DSP-based controller arbitrates between charging priority and load-supply priority under dynamic conditions (grid fail, battery low, regenerative brake event) without creating current conflicts on the shared DC bus.
Su-vastika currently holds 25+ active patents across ERD technology, including the bi-directional architecture, solar integration, IoT monitoring, and the zero-break switching algorithm. See the full list at the Su-vastika Patents & Certifications page.
Intelligent Battery Management
The bi-directional architecture enables a level of battery management impossible with conventional UPS designs. Because the controller can precisely control current in both directions, it can implement sophisticated charging profiles:
- Depth of Discharge (DoD) control: Never discharges SMF batteries below 50% or LiFePO4 below 15%, maximising cycle life
- Temperature-compensated charging: Adjusts charging voltage based on battery temperature sensors
- Float maintenance: Maintains full charge without overcharging during extended grid availability
- Equalisation: Periodically balances individual cell voltages across the battery string
- Predictive capacity estimation: Tracks actual Ah capacity vs rated, alerting when battery replacement is needed
This intelligent management directly extends battery service life — typically from 3–4 years for unmanaged batteries to 5–7 years with proper management.
Calculate Your Battery Bank Size
The bi-directional architecture handles battery sizing automatically, but you still need to spec the right battery capacity for your backup duration requirement.